dev/sg: fix sg auto-update analytics

Created by: bobheadxi

syscall.Exec will cause the current command's finalizer to not run, so we make a custom call to Persist to make sure the auto_update event is tracked in success scenarios.

Also logs unexpected error events (https://github.com/sourcegraph/sourcegraph/issues/32562) and skip events during auto-updates

Test plan

Persist works in other scenarios already!